Reflex copying method using heat developable light scattering materials



R. BAUS, JR.. ETAL 3,194,659 REFLEX COPYING METHOD USING HEAT DEVELOPABLE LIGHT SCATTERING MATERIALS Jqly 13, 1965 Filed March 6, 1961 [A/FRA RED ME R0 MT AT M E WW 2 co ULTRA-VIOLET HEAT STE/52 ATTORNEY S United States Patent REFLEX COPYING METHQD USING HEAT DE- VELOPABLE LIGHT SCATTERING MATERIALS Ren Bans, Jr., New Orleans, La., and Roy J. Lahr, l exington, Ky.; said Bans assignor to Kalvar Corporation, New Orleans, La., a corporation of Louisiana, and said 'Lahr assignor to International Business Machines Corporation, New York, N.Y., a corporation of New York Filed Mar. 6, 1961, Ser. No. 93,646

' 1 Claim. (Cl. 9647) This invention pertains to the making of copies by use of heat developable, light scattering type materials.

Materials as aforesaid and the making and use thereof and components therefor are described for example in US. Patent. 2,911,299 and pending applications of James et al., Ser. No. 623,050, filed November 19, 1956, now US. Patent 3,032,414, and Baril et al., Ser. No. 767,094, filed October 14, 1958, now US. Patent 3,149,971, assigned to one of the assignees of the present invention. These materials include a compound which is sensitive to radiation at and around the blue end of the visible spectrum usually the ultraviolets-and when exposed thereto in given areas, this compound acts to establish scatter centers when heated. Thus, in photographic terminology, exposure to form a latent image is to such blue end radiation, and development to form the latent image, is

by application of heat. No wet development is necessary, and no chemicals are then involved. The record is a permanent one, in the truest sense of the word as known in conventional photography.

Heat development as aforesaid may be accomplished by contact with a heated surfacea hot roller, or ordinary flat iron being good examples. However, since the aforesaid radiation sensitive compound is so only to the blue-end radiations, and not to the red-end ones, infrareds may be used in the heating-for-development step.

Using the scatter center, heat developable materials as aforesaid, it is known that a copy of a document may be made by first exposing a film of such material over all of its area to blue end radiations, then plying it to the document, and then irradiating the document with infrared radiations. The areas of the document which are of colors which absorb the infrared radiations then undergo an increase in temperature. The best case is a white document with black print upon it. In this case the black areas increase greatly in temperature compared to white areas. Where colors are present other than black, say reds, yellows, blues, these do not undergo as much differential temperature increase, but the effect is present to some extent, depending upon the colors involved. In the past it has been known that black characters on a white background could, by said infrared radiation, create enough heat in the black areas to heat develop the already exposed scatter center material in areas corresponding to the blacks of the document. However, it has not been possible to obtain development of colors other than blacks (and perhaps deep reds) without also developing the other areas.

It has also been known, of course, that copying in scatter center as well as other materials can be accomplished by the optical reflex method. This involves placing the copying material upon the document and irradiating this plied pair through the copying material with radiations, say ultraviolets, which expose it. A latent image in the copy occurs because the ultraviolets which pass through it but meet a character on the document are absorbed, and this one pass does not sufliciently expose these areas. However, where the ultraviolets are reflected by the document (the white areas), some make a second pass through the copy material. This second pass is sufficient to expose the copy, so that later development may be effected.

Clearly, the optical reflex operation demands close control of the intensity of the exposing radiation, lest other developable exposure occurs on one pass of the radiation, or no developable exposure occurs even for two passes.

In accordance with the present invention, the making of copies in scatter center, heat developable materials as aforesaid, by the optical reflex technique as aforesaid, is greatly improved by plying the copy material, still unexposed, to the document, and first irradiating the document (through the copy material or not) with red end radiations (normally infrareds) which have the differential heating effect mentioned above. In this way, the areas of the copy corresponding to the characters of the document are heated. Following this heating step, the optical reflex exposure step (irradiating with blue end radiations through the copy material) is carried out. It has been discovered that a greatly improved reflex copy is thusly obtained. It appears that the improved result is based upon the fact that heating of thescatter center material in certain areas decreases the sensitivity thereof to the exposing radiations. Therefore, by the time the exposure is made, the copy material is in a preferential condition such that in the regions where only one pass of the exposing radiations occurs, the sensitivity has been lowered, and developable exposure willnot occur, or is less likely to occur to any appreciable extent. However, the sensitivity in the other areas has not been diminished, and developable exposure is obtainable upon two passes of the exposing irradiations.

The attached drawing provides a pictorial representation of the preferred embodiment of the invention. Therein the scatter center type material is indicated as 10 and the document as 12. Excellent results have been obtained with material 10 made in accordance with Example I of each of the aforesaid copending applications. Reference character 14 indicates a colored area on the document. Optimum results are obtained when 14 is black. In step 1 the plied sheets are irradiated with infrareds, causing the area 14 of the material 10 adjacent area 14 to increase in temperature and reduce the sensitivity thereof as aforesaid. In step 2 the plied sheets are irradiated with ultraviolets, causing the areas 16 of material 10 adjacent the white area of 12 to become exposed due to double pass of the ultraviolets therethrough. Area 14 will not be exposed, because (1) the ultraviolets pass only down therethrough, and are absorbed and not reflected, and, (2) the area 14 has been desensitized as aforesaid. Step 3 is a conventional heat developing step following steps 1 and 2 which are the basis of this invention. Reference character 18 designates the regions of developed scatter centers. There is no need for the presence of the document 12 in step 3, although it could be present.

All scatter center materials known to date exhibit a desensitizing effect when subjected to dry heat, and thus are operable in the method described above and claimed hereinbelow. However, should scatter center materials become known which do not exhibit desensitization upon subjection to dry heat, then such are not operable, and are outside the scope of the following claims. Clearly, a very simple test of a sample of any given material may be accomplished by heating a part of it, exposing and heat developing it. Less image in the initially heated part Viilll be evidence that it is material within the following c aim.

It may be desired to have the scatter center material mounted upon a backing member. If such is present before the copying method is performed, it must be substantially transparent to the heating radiations, if same are directed through the copy material to the original. It must also be substantially transparent to the exposing radiations, to permit the optical reflex operation to be carried out, since this must be through the copy material.

The foregoing description of exemplary embodiments is intended only for purposesof illustration, and the scope of the invention is to be determined from the appended claim.

, What is claimed is:

A method of copying a document having areas of differing light absorption qualities onto a material of the light scattering, heat'developable type comprising a vehi the light struck area in said filmto thereby furnish an,

image,

, said method comprising plying the document and said material together, irradiating the document with ra-.

diationsin the regions of the red end of the spectrum to which said material is substantially not sensitive, and then irradiating the plied document and material with said radiations in the region of the blue end of m'aterialof improved contrast. V

References Cited by the Examiner UNITED STATES PATENTS 1,997,507 4/35 Akintievsky 9649 2,684,341 7/54 Anspon et al.

2,703,756 3/55 Herrick et a1 9649 2,740,895 4/56 Miller I 260--65.l 2,916,622 12/59 Nieset L117-36.8 X 2,950,194 8/60 Glavin .'96'49 X 2,993,805 7/61 Kay Q 96- -49 X 2,995,466 8/61 Sorensen -2; 117-3618 3,032,414 5/62 James et a1 96-49 X 3,042,517 7/62 Wainer 96-90 X FOREIGN PATENTS 815,005 6/59 Great Britain. t

OTHER REFERENCES IBM Technical Disclosure Bulletin, Duplicating Film, R. S. Haines, volume 3, No.9, February l9t6l,--page 1. NORMAN G. TORCI- IIN, Primary Examiner, PHILIP E. MANGAN, Examiner. 

